Insole



Get. 9, 1956 F. G. RINECKER INSOLE Fi led Dec. 28, 1954 INVENTOR. [IPA/V2 6. ,P/A/[Ckf/F irratWiYs INSOLE Franz G. Rinecker, Dayton, ()hio, assignor to the United States of America as represented by the Secretary of the Air Force Application December 28, 1954, Serial No. 478,215 11 Claims. (Cl. 154-46) (Grated under Title 35, U. S. Code (E52), sec. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to an insole for footwear. More particularly the invention relate to plied insoles designed to maintain their resiliency even at subzero temperatures in the presence of moisture.

It is an object of this invention to provide a plied insole having monofilament screen incorporated therein wherein the edges of the screen have been sealed or bonded by heating or other means so the free-ends of the screen do not protnlde and cause discomfort to the feet of persons wearing shoes containing the insole.

Another object of this invention is to provide a resilient insole having long wear characteristics.

Still another object of this invention is to provide an insole which dries out much more rapidly than the conventional insole due in part to needled fibers from the outer layers being present in the inner layers of the insole.

A further object of this invention is to provide a multiple layer or ply insole wherein the layers do not tend to shift or be displaced relative to one another.

A particular object of the invention is to provide an insole wherein moisture tends to remain on the surface of the insole and not penetrate into the central layer or layers of the insole, so the insole tends to remain resilient and flexible even at subzero temperatures in the presence of moisture.

The above objects and other objects which will be apparent from the detailed description of the invention are accomplished by the invention which is a plied insole comprising one or more inner layers of resilient unspun fibers which will absorb no substantial amount of moisture, one or more inner layers of monofilament screen, and at least one of the outer layers comprising a major amount of resilient nonthermoplastic fibers which will absorb a substantial amount of moisture mixed with a minor amount of thermoplastic fibers which have substantial mechanical strength. Some of the fibers of fiber layers extend into and interlock with fibers in other fiber layers to form an insole wherein the layers do not tend to be displaced relative to one another. It is preferred that the edges of the insole be sealed to protect the feet of the wearer of shoes containing these insoles against uncomfortable contact with the free-ends of the monofilament screen.

The inner or central layer or layers of the insole are made or" unspun fibers having substantial resiliency or good recovery characteristics and low moisture absorption. Any nonthermoplastic fiber or thermoplastic fiber meeting these requirements would be satisfactory.

One type of fiber which is particularly satisfactory for the inner or central layer is synthetic polymeric amide fiber, which is made from long-chain synthetic polymeric amides having recurring amide groups as an integral part of the polymer chain. Nylon fibers made by the du ice? Font Company is a particularly suitable example of this type of fiber.

A second type of satisfactory fiber for the inner or central layers is long-chain polyester of terephthalic acid and ethylene glycol fiber. An example of this type of fiber is Dacron marketed by the du Pont Company.

Monofilament screen suitable for use in the insole is normally made from monofilament produced by extruding a suitable material. Weave patterns normally used for this screen are plain Weave or twill weave. Obviously there are other types of weave patterns which would be satisfactory.

Any monofilament which has substantial mechanical strength is satisfactory for making these screens. That is, these screens might be made from either nonthermoplastic or thermoplastic materials. Two particularly suitable materials for making these screens are Nylon which is synthetic polymeric amide made by the du Pont Company and Saran which is a copolymer of vinylidene chloride and vinyl chloride made by the Dow Chemical Company. The proportions of vinylidene chloride and vinyl chloride used in Saran are about 85% by weight and 15% by weight, respectively.

One or both of the outer layers are composed of a mixture of nonthermoplastic and thermoplastic unspun fibers. The nonthermoplastic fibers make up the greatest part of the outer layer with the thermoplastic fibers being present in a sufiicient amount to provide substantial mechanical strength in the outer layer. The nonthermoplastic fibers usable in the outer layers must have substantial moisture absorbing properties. The thermoplastic fibers useful in the outer layers are those having substantial mechanical strength. It is preferred to use from about 70 to about by weight of nonthermoplastic fibers and from about 20% to about 30% by weight of thermoplastic fibers in the outer layers.

Particularly suitable nonthermoplastic fibers for the outer layers are made from proteins such as casein, corn, peanut, soy bean, and gelatin proteins.

A particularly suitable fiber made from corn protein is Vicara marketed by the Virginia-Carolina Chemical Corporation. Vicara is made from zein which is the prolamine fraction of corn protein. Vicara fibers have substantial resiliency and will absorb a substantial amount of moisture.

A casein fiber which is suitable for the outer layer is Lanital made by Snia Viscosa, Milan, Italy.

The thermoplastic fibers for the outer layer should have substantial mechanical strength and should absorb no substantial amount of moisture. If the mechanical strength of the thermoplastic fibers were maintained, even in the presence of moisture, however, there would be no objection to the thermoplastic fibers absorbing a substantial amount of moisture. These fibers are added primarily to give mechanical strength to the outer layer.

Two examples of suitable thermoplastic fibers are: Nylon fibers which are synthetic polymeric amide fibers made by the du Pont Company, Dacron fibers made from long-chain polyester of terephthalic acid and ethylene glycol by the du Pont Company.

Fibers for the fiber layers may vary substantially in staple length and denier depending on the material from which the fibers are made and the method of making. It is specified that fibers be of suitable staple length and denier depending on the characteristics of the fiber and for use in insoles. The unspun fibers whether of fibers made from the same material or a mixture of fibers made from different materials are fabricated into fiber batts by conventional means well known in the art.

Fiber batts made of suitable material for the inner and outer layers of the insole together with monofilament screen are assembled and attached by a conventional needling operation, i. e., by pricking through the fiber batts with needles which serve to carry some of the fibers ofv one fiber layer into the adjacent fiber layer. The preferred method of assembling the insole is to take two fiber batts with a screen in between and needle them together to form two fiber layers of the insole. Additional layers are then needled on one at a time. Normally the needling will be done from one side only in combining the layers. Thereby, an insole is produced having good structural stability.

Normally it will be preferred to form multiple layer material for the insoles from large sheets of screen and large fiber batt layers. The individual insoles will then be cut or stamped from these large multiple sheets. The needling to join the layers is done before making the individual insoles.

The sealing of the edges of the individual insoles may be accomplished by bonding the edges with a suitable resin, heat searing the edges, or other suitable means. If heat searing is used it may be accomplished on the individual insoles with a heated rod or other suitable means, or the searing may be accomplished by the heated cutting or stamping device at the time the individual insoles are formed.

For a more complete understanding of the nature and objects of the present invention reference should be made to the accompanying drawing in which:

Fig. 1 is a perspective view of an insole embodying the invention; and

Fig. 2 is a cross sectional view of the insole taken along the lines -22 of Fig. l; and

Fig. 3 is a cross sectional view of an insole having two inner fiber layers.

The insole in its entirety is designated by an arrow as insole 11 wherein the central layer 12 is shown sand wiched between two layers of monofilament screen 13. Outer layers 14 cover the monofilament screen and the central layer.

Fig. 2 shows in detail the construction of the insole. Central layer 12 is made of unspun synthetic polymeric amide fibers. The monofilament screen layers 13 are made of extruded synthetic polymeric amide monofilament, and the weave of the screen is known as a plain weave. Outer layers =14 are made of about 75% by weight prolamine fraction of corn protein unspun fibers plus about 25% by weight synthetic polymeric amide unspun fibers. The effect of the needling process on the insole is illustrated by fibers 1'5. Needling in this instance was accomplished by needling from each outer layer into the inner layer carrying fibers of the outer layers into the inner layer.

Insole 11 has a central fiber layer which will absorb no substantial amount of moisture; whereas, the outer layers l4'containing 75% by weight corn protein fibers will absorb substantial amounts of moisture. This means that when the insole subjected to substantial amounts of moisture, either in the form of sweat from the feet of the wearer of shoes containing these insoles or from the outside through the sole of the shoe, the moisture will to remain in the outer layers. Resiliency of the insole will be maintained to a large degree at least in the central layer which will absorb no substantial amount of water. When there is an opportunity for the insole to dry out, the insole of the invention will dry out much faster than the normal insole and as it dries even the small amount of moisture retained by the central layer will quickly be transferred to the outer layers due to the much greater tendency of the outer layers to absorb moisture. There will be no substantial tendency of the insole to wet through from one side to the other due to the tendency of the central layer to absorb no substantial amount of moisture. Also the high moisture absorbing corn protein fibers, present in the central layer as a result of needling, will act as wicks to speed the transfer of moisture to the outer layers and so the drying out of the insoles.

When the insoles have become quite wet as by submersion in water, the drying of the insole may be speeded in below freezing weather by removing the insoles from the shoes, placing the insoles out-doors till the water in them freezes, vigorously bending the insole back and forth to crack off the surface and near surface ice, and placing the insole near a heater to dry out the remaining moisture.

If it is desired to have a particularly thick insole, more than one inner layer may be used. Fig. 3 shows an insole having two inner layers. Inner layers 16 are made of unspun synthetic polymeric amide fibers. A layer of monofilament screen 17 made of extruded synthetic polymeric amide monofila-ment is placed between two layers of synthetic polymeric amide fiber batt and the layers formed by needling from one fiber batt into the other.

Next the two inner layers are sandwiched between two layers of monofilament screen 17 and the outer layers 1-8 are formed by needling from a fiber batt into the adjacent inner layer. The fibers of the outer layers contain about 75 by weight prolamine fraction of corn protein unspun fibers and about 25 by weight synthetic polymeric amide unspun fibers. Fibers 20 illustrate needled fibers joining the inner layers and fibers 19 illustrate needled fibers joining the outer layers to the adjacent inner layer.

While the present invention has been described by reference to preferred embodiments thereof the same have been given by way of illustration only and are not intended to limit the invention which includes within its scope such modifications and variations as come within the scope of the appended claims.

I claim:

1. A plied insole comprising at least one inner layer of resilient unspun fibers which will absorb no substantial amount of moisture, a layer of monofilament screen on each side of each inner layer, outer layers at least one of which comprises a major amount of resilient nontherm'oplastic unspun fibers which will absorb a substantial amount of moisture mixed with a minor amount of thermoplastic unspun fibers which have substantial mechanical strength, and a plurality of fibers from fiber layers extending into and interlocking with fibers of other layers in such a fashion that said layers are attached to form said insole wherein the layers do not tend to be displaced relative to each other.

2. The insole of claim 1 wherein the nonthermoplastic fibers of said outer layer are protein fibers.

3. The insole'of claim 1 wherein the fibers of said inner fiber layer are synthetic polymeric amide fibers, said screen is formed of extruded synthetic polymeric amide monofilament, the nonthermoplas-tic fibers of said outer layer are prolamine fraction of corn protein fibers and the thermoplastic fibers of said outer layer are synthetic polymeric amide fibers.

4. The insole of claim 1 wherein the fibers of said inner fiber layer are long-chain polyester of terephthalic and ethylene glycol fibers, said screen is formed of an extruded monofilament made of copolymer of a mixture of a major amount of vinylidene chloride and a minor amount of vinyl chloride, the nonthermoplastic fibers of said outer layer are casein fibers and the thermoplastic fibers of said outer layer are long-chain polyester of terephthalic acid and ethylene glycol fibers.

5. A .plied insole comprising a central layer of unspun resilient thermoplastic fibers which will absorb no substantial amount of moisture, a layer of monofilament screen on each side of said central layer, outer layers of unspun mixed fibers comprising from about 70% to about by weight of nonthermoplastic fibers having substantial moisture absorbing capacity and from about 20% to about 30% by weight of thermoplastic fibers having substantial mechanical strength, a plurality of fibers of eachouter unspun fiber layer extend into and interlock with fi-bers of said central fiber layer to form said insole wherein the layers do not tend to be displaced relative to each other, and said insole has sealed edges.

6. The insole of claim 5 wherein the fibers of said central layers are synthetic polymeric amide fibers, said screen is formed of extruded synthetic polymeric amide monofilament, said nonthermoplastic fibers of the outer layers are prolamine fraction of :corn protein fibers, and said thermoplastic fibers of the outer layers are synthetic polymeric amide fibers.

7. The insole of claim 5 wherein the fibers of said central layer are long-chain polyester of terephthalic acid and ethylene .glycol fibers, said screen is formed of an extruded monofilament made of copolymer of a major amount of vinylidene chloride and minor amount of vinyl chloride, said nonthermoplastic fibers of the outer layers are casein fibers, and said thermoplastic fibers of the outer layers are long-chain polyester of terephthalic acid and ethylene glycol fibers.

8. A plied insole comprising two inner layers of unspun resilient thermoplastic fibers which will absorb no substantial amount of moisture, a layer of monofilament screen on the outside surface of each of said inner fiber layers :and a layer of monofilament screen between said inner fiber layers, outer layers of unspun mixed fibers comprising from about 70% to about 80% by weight of nonthermoplastic fibers having substantial moisture absorbing capacity and from about 20% to about 30% by weight of thermoplastic fibers having substantial mechanical strength, a plurality of fibers from one inner fiber layer extend into and interlock with fibers of the other inner fiber layer and a plurality of fibers from each of said outer fiber layers extend into and interlock with fibers of the adjacent inner fiber layer to form said insole wherein the layers do not tend to be displaced relative to each other, and said insole has sealed edges.

9. The insole of claim 8 wherein the fibers of said 6 inner fiber layers are synthetic polymeric amide fibers, said screen is formed of extruded synthetic polymeric amide monofilament, said non-thermoplastic fibers of the outer layers are prolarnine fraction of corn protein fibers, and said thermoplastic fibers of the outer layers are synthetic polymeric amide fibers.

=10. "The insole of claim 8 wherein the fibers of said inner layers are long-chain polyester of terephthalic acid and ethylene glycol fibers, said screen is formed of an extruded monofilament made of copolymer of a major amount of vinylidene chloride and a minor amount of vinyl chloride, said nonthermoplastic fibers of the outer layers are casein fibers, and said thermoplastic fibers of the outer layers are long chain polyester of terephthalic acid and ethylene glycol fibers.

1-1. A plied insole comprising at least one inner layer of resilient unspun fibers which will absorb no substantial amount of moisture, a layer of monofilament screen on each side of each inner layer, outer layers at least one of which comprises a major amount of resilient nonthermoplastic unspun fibers which will absorb a substan tial amount of moisture mixed with a minor amount of thermoplastic .unspun fibers which have substantial mechanical strength, a plurality of fibers from fiber layers extending into and interlocking with fibers of other layers in such a fashion that said layers are attached to form said insole wherein the layers do not tend to be displaced relative to each other, and said insole having sealed edges.

References Cited in the file of this patent UNITED STATES PATENTS 2,331,321 Heaton Oct. 12, 1943 2,425,388 Oestricher Aug. 12, 1947 2,495,045 Woodbury et a1. Jan. 17, 1950 2,543,101 F-rancis Feb. 27, 1951 2,591,490 Allen Apr. '1, 1952 

11. A PLIED INSOLE COMPRISING AT LEAST ONE INNER LAYER OF RESILIENT UNSPUN FIBERS WHICH WILL ABSORB NO SUBSTANTIAL AMOUNT OF MOISTURE, A LAYER OF MONOFILAMENT SCREEN ON EACH SIDE OF EACH INNER LAYER, OUTER LAYERS AT LEAST ONE OF WHICH COMPRISES A MAJOR AMOUNT OF RESILIENT NONTHERMOPLASTIC UNSPUN FIBERS WHICH WILL ABSORB A SUBSTANTIAL AMOUNT OF MOISTURE MIXED WITH A MINOR AMOUNT OF THERMOPLASTIC UNSPUN FIBERS WHICH HAVE SUBSTANTIAL MECHANICAL STRENGHT, A PLURALITY OF IFBERS FROM FIBER LAYERS EXTENDING INTO AND INTERLOCKING WITH FIBERS OF OTHER LAYERS IN SUCH A FASHION THAT SAID LAYERS ARE ATTACHED TO FORM SAID INSOLE WHEREIN THE LAYERS DO NOT TEND TO BE DISPLACED RELATIVE TO EACH OTHER, AND SAID INSOLE HAVING SEALED EDGES. 